     (wrap library-signature "Ausleihe: ")))
 
 (defn- verkauf
-  [product-number price]
-  (when product-number
+  [{:keys [product-number price price-on-request?]}]
+  (when (or product-number price-on-request?)
     (str "Verkauf: "
          (wrap price "" ". " false)
          (layout/braille-signatures product-number))))

     (wrap producer-brief "" ", Hörbuch aus dem Handel")
     (producer-str producer-brief))
   (ausleihe-simple library-signature)
   (when product-number
     (str "Verkauf: " product-number ", " price))))

(defmethod entry-str :grossdruck
  [{:keys [genre-text description library-signature volumes product-number price] :as item}]
  (join
   (entry-heading-str item)
   (genre-str genre-text)
   (description-str description)
   (when library-signature
     (str "Ausleihe: " library-signature (wrap volumes ", " " Bd. " false)))
   (when product-number
     (str "Verkauf: " price))))

(defmethod entry-str :e-book

   (description-str description)
   (wrap game-description)
   (ausleihe library-signature)
   (verkauf item)))

(defn- level-str [items path path-to-numbers]
  (str
